Hi pooja,
You are making several mistakes, but the most important is
that your unit cell contains 2 atoms, whereas you' re telling
50 to fcbuild.
Of course, siesta used a 50 atoms cell to obtain the FC matrix,
because of,
SuperCell_1 2
SuperCell_2 2
SuperCell_3 0
that make a supercell of 5x5x1 unit cells.
My suggestion in short, replace "NumberOfAtoms 2", and tell
(fcbuild + vibra) the coordinates of those 2 atoms (25 and 26
apparently, in your FC.fdf file). Run vibra with the graf.FC
you've got.
This might already work; if it doesn't, read the docs for the
vibra package carefully, making sure you understand.
If it does work, read the docs too, it pays ;) .
Cheers,
Roberto
On 10/03/2015 02:53 AM, pooja pu wrote:
hello,
yes my *.FC file has 601 rows...... the first row has "Force Constant"
written and then it has 600 rows with 3 collumn....
here is that .FC file and a input FCbuilder fdf.
thanks
pooja
On Fri, Oct 2, 2015 at 6:10 PM, RCP <[email protected]> wrote:
Just a small bit: strictly your FC file must containt 600+1 rows.
R.
On 10/02/2015 09:28 AM, pooja pu wrote:
Hello
Yes it has two atoms in the unit cell the fcfirst and fclast are at 26
and 27 atom.
Thanks a lot
Pooja
On 2 Oct 2015 17:50, "RCP" <[email protected]
<mailto:[email protected]>> wrote:
>
> Hi,
>
> So, how big is your (vibrating) unit cell ?, 50 atoms ?.
> Each atom of the unit cell is responsible for 6*50=300
> rows in the *.FC file. Thus, for 600 rows you must have
> a unit cell of 2 atoms. I bet this is not what you want;
> probably your FCfirst and/or FClast are wrong.
>
> Regards,
>
> Roberto
>
>
> On 10/02/2015 06:39 AM, pooja pu wrote:
>>
>> hello all,
>>
>> i am currently trying to obtain phonon spectra using Vibra utility. i
>> took a 2x2x0 graphene supercell with 50 atoms and run it obtained a
*.FC
>> file with 600 rows. But on running vibrator i got the following error
>>
>> Computing Eigenvalues and Eigenvectors
>> At line 322 of file vibrator.f (unit = 12, file = 'graf.FC')
>> Fortran runtime error: End of file
>>
>>
>> can anybody tell what may be the possible reason.. any help is highly
>> acknowledged...
>>
>>
>> thanks
>>
>> pooja
